Anatomical concentric spheres THA

Abstract

Devices and methods for identifying and maintaining the concentric spherical centers of a femur and acetabulum during revision or joint replacement surgery so that post surgery the anatomical spherical centers are maintained. Also disclosed are novel techniques and devices to project images onto an anatomical feature, such as exposed bone, to virtually fit trial prosthetic components, establish bone cut markings, and establishing the anatomical spherical center of a joint.

What is claimed is: 
     
       1. A trial for use with total hip arthroplasty, the trial comprising:
 a first spherical insert having a plurality of tabs mounted thereto, each of the plurality of tabs at least partially defining an orifice, wherein the first spherical insert is sized to fit within an unreamed acetabulum, the first spherical insert further being sized to contact the acetabulum and a resected femoral neck when the first spherical insert is positioned within the unreamed acetabulum. 
 
     
     
       2. The trial of  claim 1 , wherein the first spherical insert includes a first semispherical half and a second semispherical half that engage and disengage one another. 
     
     
       3. The trial of  claim 2 , wherein the first semispherical half engages the second semispherical half along an equator of the first spherical insert. 
     
     
       4. The trial of  claim 3 , wherein the plurality of tabs extend outwardly from the first semispherical half adjacent to the equator. 
     
     
       5. The trial of  claim 1 , wherein the orifice of each of the plurality of tabs is sized to receive a pin. 
     
     
       6. A surgical instrument for use in a hip arthroplasty, the surgical instrument comprising:
 a body including a first piece removably coupled to a second piece, each of the first piece and the second piece having a convex curved outer surface, and 
 a plurality of tabs extending outward from the body, each tab having an orifice defined therein that is sized to receive a pin, wherein the body is sized to fit within an unreamed acetabulum, the body further being sized to contact the acetabulum and a resected femoral neck when the body is positioned within the unreamed acetabulum, 
 wherein the convex curved outer surfaces of the first piece and the second piece define a sphere when the first piece is coupled to the second piece. 
 
     
     
       7. The surgical instrument of  claim 6 , wherein each tab of the plurality of tabs extends outwardly from the first section of the spherical outer surface and the second piece is devoid of any of the plurality of tabs. 
     
     
       8. A surgical instrument for use in a hip arthroplasty, the surgical instrument comprising:
 a body having an outer surface that defines a sphere, and 
 a plurality of tabs extending radially outward from the outer surface, each tab having an orifice defined therein that is sized to receive a pin, wherein the outer surface of the body is sized to fit within an unreamed acetabulum, and the outer surface of the body further being sized to contact the acetabulum and a resected femoral neck when the body is positioned within the unreamed acetabulum. 
 
     
     
       9. The surgical instrument of  claim 8 , wherein the body includes (i) a first piece and (ii) a second piece removably attached to the first piece at a circular edge of the first piece. 
     
     
       10. The surgical instrument of  claim 9 , wherein the plurality of tabs extend radially outward from the first piece at the circular edge.